It is often remarked upon that serpaens are contradictory creatures. These companions possess the temperaments of loyal dogs, but have slender bodies like those of snakes. Their very existence is a mystery, as no mention of them has been found in the library, and no tales of them are told. Many think that these creatures must be distantly related to alphyns, a plausible idea as they do indeed resemble alphyns in various ways. These companions live across the lands, from the south near Voltar to the edges of the western forests. Serpaens always choose areas that are difficult to travel to, or very dangerous. To the south, they make their homes where the weather is arid and sand storms often arise. Hardly anyone wanders into these harsh deserts, so Voltarian serpaens are rarely spotted. Silvan serpaens choose woods full of predators, where the trees grow so tall that sunlight cannot reach. Fully grown serpaens consume anything that moves, and when no other food is available, will eat plants. While adult serpaen surface and hunt, hatchlings are more hesitant to move around above ground. At the castle, young serpaens must be socialized, lest they snap at other companions. These serpaens come in one of four distinctive colors, and each variety has subtle personality differences. Silvian serpaens are light green in color, with a long brown mane. Two are yellow in color; the Savannah serpaen, with an orange mane, and the Etanian serpaen, which boasts a short brown mane. The last color variation possesses a single sharp horn, and does not care for the company of humans, though with time it warms to its magi. It is called the arcanum serpaen, and it takes great care to keep its origin a mystery.

Despite their fierce appearances, serpaens are loyal, friendly companions. They bond closely with their magi, and will guard them against any threat. There are many accounts of these companions endangering themselves in order to save others lives, especially those of children. While this makes these serpaens excellent company when exploring to the south, they do not care for the castle. Instead, they remain below ground. Most of them prefer to dwell in one of the several deserts that have been magically created for them. Others choose different soil, closer to the forest. Though these serpaens are not often seen above ground, they will lounge around in the summer, soaking up the sun. They despise the rainy seasons, and months sometimes go by when they are not sighted. Serpaens travel through sand and soil with the same ease as a fish moves through water. It is thought that they prey upon whatever creatures they find below the earth, and surface from time to time for other sustenance. Sometimes these companions produce small flames, charring their food. These flames, while not large, burn hot enough to melt sand and form glass. This glass is full of bubbles, and considered very beautiful. A few magi extensively study serpaens, and have found evidence that these companions form large chambers with this glass, with small tunnels providing air.